A key component in semiconductor application is a solid-state switch. As an example, switches turn loads of automotive applications or industrial applications on and off. Solid-state switches typically include, for example, field effect transistors (FETs) like metal-oxide-semiconductor FETs (MOSFETs) or insulated gate bipolar transistors (IGBTs).
In order to realize self-protecting MOS power switches, it is customary inter alia to integrate a current sensor. The current sensor may be realized as a small sensor transistor, which supplies a current proportional to the load current flowing through the load transistor. The sensor transistor is substantially smaller, e.g. a factor of 1000-10 000 smaller than the load transistor, and a sensor current flowing through the sensor transistor is smaller than the load current through load transistor ideally by the geometrical ratio of the active areas of the two transistors, namely the load transistor and the sensor transistor.
In an operating state, load and sensor currents may lead to a different increase of local temperature within the device due to different cooling capabilities of the load current component and the sensor component. An excessive increase of temperature within the sensor component may lead to a deterioration of the sensor component.
It is thus desirable to improve an operating characteristic of the sensor component integrated in the load current component.